Power-electronic interfacing based devices such as photovoltaic (PV) panels and electric vehicles (EVs) cause voltage/current harmonic distortions on the power grid. The harmonic current profiles from EVs and PVs depend on the design of the controllers integrated to the PV inverters and EV chargers. Similarly, the voltage and current harmonic distortions on a grid change throughout the day as the PV output power, number of grid connected EVs, and the other load pattern change. In this context, we present harmonic assessment to demonstrate cumulative effect of large number of EVs and PVs on a medium voltage distribution grid. We will demonstrate the case studies on the IEEE 123-node distribution feeder with 20%, 50%, and 100% PV and EV penetrations, based on time series simulations carried out for an entire day.